Do a search on eBay for seller ID "interslice" (Jon Goodman). Get the $6.00 kit, which he ships free within the USA. High quality materials, a "Camera Seal Repair for Dummies" instruction sheet (okay - he doesn't call it that, but you get the idea), and a "tool" for removing the old seals. Has enough material for several cameras.

Anyone who's used Jon Goodman's kits, are they modular or do you order for specific cameras? I've got some aging film backs that could use some new seals, and this seems like the one repair I could probably trust myself to to do.